School bus seat frame back attachment

ABSTRACT

A modified seat frame provides a seat back and lower frame on which the seat back may be mounted. The lower frame includes risers with support necks for receiving the seat frame.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to school bus seats and more particularly to a joint system for attaching seat back frames to the remainder of the seat frame sub-structure.

2. Description of the Problem

School bus seats are built to meet many differing customer specifications. For example, some bus seats must accommodate three point safety belts by providing a compatible upper back rest, other specifications call for a universal child restraint attachment equipped lower frame, while still others provide standard DOT (United States Department of Transportation) seat backs. Alternatively, customers can specify seats in different widths or heights and can demand various strength requirements. School bus passenger seats vary in height and width resulting in different seat back performance characteristics.

Differing customers' specifications have required substantially or entirely different component sets. The need to supply such component sets has even occurred relative to completed vehicles that have been put into service where the vehicle has been moved from one state or municipality to another, based on differing requirements of the new jurisdiction. The variability in size has contributed to varying component sets meant to meet strength standards. Multiple tubes, brackets and gussets are incorporated into welded seat assembly. Components were added to the various seat assemblies until the resulting design was compliant. Various seat widths and heights may use different hardware based on these changes. Therefore, seats have exhibited additional variation in component parts to meet the FMVSS 222 requirements.

Representative of prior art school bus seat frame systems are those of FIG. 2 and U.S. Pat. No. 6,886,889. The system of FIG. 2 is characterized by a large number of parts and a need for a substantial amount of welding for assembly, which in turn limits flexibility in outsourcing. This occurs because the 1) frame assembly does not package well for shipping, 2) the welded design dictates painting after assembly and (3) it is difficult to outsource sub-assemblies because they have been entirely welded (creating problems for fit and paint matching). This means that if the entire seat frame assembly is outsourced, it must be shipped in a complete condition, which does not nest or package well. Also, because the entire assembly is welded, paint must be applied after the frame assembly is complete.

SUMMARY OF THE INVENTION

The invention provides for a seat frame built from subassemblies that attach at joints. These joints are able to accept fasteners, thereby eliminating welding operations, and allowing the subassemblies to be stocked in a painted condition. The minimum level of subdivision of the seat frame is into two sections, a seat back and a lower frame. The lower frame includes risers with receiving necks into which the seat back can be mounted. The seat back includes a partial perimeter framing tube which ends in rectangular sections which are engaged in the necks extending from the lower frame. The lower riser has the stamped section that accepts the upper seat frame square tube. Components are easily stackable and shipable, and may be shipped in a painted condition. Assembly is accomplished with conventional fasteners, and easy to use hand tools. In addition, the system lends itself to automated assembly steps.

Additional effects, features and advantages will be apparent in the written description that follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself however, as well as a preferred mode of use, further objects and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein:

FIG. 1 is a perspective view of a school bus.

FIG. 2 is a perspective view of a prior art school bus seat frame.

FIG. 3 is a perspective view of a modular school bus seat frame incorporating the present invention as installed in a vehicle.

FIG. 4 is an exploded view of the school bus seat frame illustrated in FIG. 4.

FIG. 5 is perspective view of two sub-assemblies for a school bus seat frame.

FIG. 6 is an exploded view of a joint between a riser and a seat back perimeter tube in which the reinforcement element of the present invention may be placed.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings and in particular to FIG. 1, a school bus 10 with which the present invention is advantageously used is illustrated. The seat frames of the present invention are installed in the interior 18 of the bus.

FIG. 2 illustrates a prior art seat frame 20 including a closed circuit, multi-piece, full perimeter tube 26. Perimeter tube 26 forms an “L” outlining a base seat and seat back for the bus seat frame 20. The perimeter tube 26 is supported by an aisle riser 22 and a wall riser 24. An internal frame 28 and a back seat support 30 are nestled within the closed perimeter tube 26. Excluding the risers 22, 24, few of the components are reusable should seat specifications, such as width, or height of the seat back be changed. Any change necessitates a change in the perimeter tube 26 and an internal frame 28 parallels portions of the perimeter tube 26, reinforcing the sides of the perimeter tube and adding a seat back bottom brace 34 and a cross member 32 to give the frame 20 rigidity.

Referring to FIG. 3, an assembled modular school bus seat frame 40 is illustrated supported in part from the floor 42 (shown in phantom) and along interior bus wall 44 (shown in phantom) from a chair rail 62 formed on the interior wall 44. Support from the floor 42 is provided by an aisle riser 46. Support from the wall 44 is provided by a wall riser 48. Aisle riser 46 and wall riser 48 differ from the aisle risers and floor risers known from the art illustrated in FIG. 2 in that they form more of the seat frame than is traditional in school bus applications. Both the aisle riser 46 and the wall riser 48 are modified to function as frame elements, in part by inclusion of necks 50 which provide bases of support for an open ended, partial perimeter tube 52 used to define the top and sides of a seat back portion of frame 40. The partial perimeter tube 52 is an upside down U shaped structural member mounted at opposite ends in necks 50 and defines the top and sides of the seat back. Suspended on and within the partial perimeter tube 52 is a seat back panel 54. Extending between and fitted into the aisle riser 46 and the wall riser 48 are front and back latitudinal supports 60 and 56. Supports 56 and 60 come in varying lengths to support seats of varying widths and fit into the risers to form joints. Risers 46 and 48 are molded elements with interior (i.e. facing) sides which are contoured to reinforce the riser.

FIG. 4 is an exploded view of the modular seat frame 40 which shows the major structural members of the seat frame. Necks 50 provide the location of the junction between the ends of the seat back perimeter tube 52 and the risers and are the locations where variable length reinforcement members 64 are located upon assembly of the seat frame 40. Necks 50 are C-channel sections extending upwardly from the upper rearward areas of aisle riser 46 and wall riser 48 and formed during the stamping process used to fabricate the risers. The open faces of the necks 50 face one another. Partial perimeter tube 52 outlines the top and sides of the seat back, having two substantially right angle bends in the tube, but is open at the bottom terminating in two spaced ends. The spaced ends fit into the necks 50 to support the seat back. The joints formed by joining the ends of the perimeter tube 52 to the necks 50 may be reinforced by addition of reinforcement members 64 which fit into the neck 50 sandwiched between the tube 52 and the interior of the necks 50. Bolts 66 are inserted through the walls of the necks 50, reinforcement members 64 and the ends of perimeter tube 52 to complete the assembly.

Back panel 54 includes a partial perimeter lip 74 by which the panel is attached to tube 52. Risers 46, 48 include inner face contours 76 which position the ends of rear and front supports 56, 60. Risers 46, 48 have integral inwardly turned flanges 78 along their top and front edges. In addition, risers 46, 48 have a back edge flange 71, which are also inwardly turned. Flanges 71 and 78 provide surfaces against which opposite surfaces of the front and rear cross members 60, 56 may be placed to be secured by self pierce rivets (not shown), or other methods such as low temperature welding. Front cross member 60 is substantially formed in three panels, front panel 61, intermediate panel 63, and top panel 65 with panel 63 being intermediate to panels 61 and 65. The angle between panels 61 and 65 corresponds to the angle between the front and top edge sections of flange 78, allowing the cross member to be brought into contact with both portions of the flange concurrently. Panel 63 intersects both panels 61 and 65 obliquely along the respective interior side (i.e. the underside of the member relative to the risers) and positioned between the two panels functions as a cross brace between the flange 78 portions.

Rear cross member 56 incorporates two major sections, a top section 57 and a back section 59. The ends of top section 57 and back section are angled (essentially a right angle) to allow them flush mating of the sections to the under surface of the top portion of flange 78 and the forward surface of flange 71. Self pierce rivets (not shown), glue or welding are used to connect the member to the riser.

Aisle riser 46 includes legs which support the structure from the floor. A plate 68 is provided for securing fasteners between the riser 46 and a vehicle floor. Wall riser 48 includes an attachment lip 72 allowing securing of the wall riser to a wall support. Plate 68 and washer 70 are provided as part of the attachment process. FIGS. 5 and 6 illustrate alternative partial fabrications of the modular seat frame, the system of FIG. 5 providing for delivery for installation in two sections 80, 82. Section 80 includes perimeter tube 52, its reinforcing braces and back seat support 54. Section 82 comprises risers 46 and 48 and the longitudinal braces 56 and 60.

FIG. 5 illustrates the two section partial fabrication of the modular seat frame, with the seat frame divided into two sections, a lower sub-assembly 82 and a seat back 80. Seat back sub-assembly 80 includes a rectangular section, partial perimeter tube 52 and a back seat support 54. Section 82 comprises risers 46 and 48 and the longitudinal braces 56 and 60. As already described, risers 46 and 48 include necks for receiving the ends of the rectangular section, partial perimeter tube 52.

FIG. 6 illustrates assembly of one of the joints used to join seat back sub-assembly 80 to lower seat frame 82. A reinforcement member 64 may be fitted between fits sandwiched between the perimeter tube 52 and necks 50 of risers 46 and 48 (only riser 46 is illustrated, though the member would typically be used identically with riser 48). Where reinforcement members 64 are used the dimensions of the necks 50 can be increased, or the dimensions of the partial perimeter tube 52 can be decreased, to accommodate the reinforcement member 64 between the tube and inside of the neck. Without the reinforcement member 64 the ends of the perimeter tube 52 fit snugly into the necks 50.

Stamped seat risers 46, 48 in the lower frame sub-assembly 82 are formed to accept the perimeter tube 52 of the seat back sub-assembly 80. Features on the riser and perimeter tube are self-aligning and provide a significant surface area along which the interior of the necks 50 and the ends of tube 52 meet. This supports clamping and formation of the joint between the seat back and the lower seat frame. This joint takes advantage of the stamped seat risers by providing the formed sections (i.e. necks 50) that accept ends of the perimeter tube 52 of the seat back sub-assembly 80. The features on the riser and the perimeter tube are self-aligning, and provide sufficient clamping surface to allow the seat to meet the strength requirements that are needed for the seat to perform correctly in accident situations. It also takes advantage of having a square cross-section at the interface. This distributes clamp loads, tolerates manufacturing variability, and allows the use of standard square tubing. Joining may be completed using bolts 66, MIG welds, adhesives, etc.

Components are easily stackable and shipable, and may be shipped in a painted condition. Assembly is accomplished with conventional fasteners, and easy to use hand tools. Alternately, the same design lends itself to automated assembly.

While the invention is shown in only one of its forms, it is not thus limited but is susceptible to various changes and modifications without departing from the spirit and scope of the invention. 

1. A modular seat frame comprising: a lower frame sub-assembly including a first riser having a first open support neck and a second riser having a second open support neck; a seat back sub-assembly including an upside-down U shaped partial perimeter tube supported by the first riser and the second riser at joints formed between opposed ends of the upside-down U shaped partial perimeter tube and the first open support neck and the second open support neck; and the opposed ends of the upside-down U shaped partial perimeter tube conforming to interior shape of the first neck and the second neck.
 2. The modular seat frame as claimed in claim 1 wherein the lower frame sub-assembly and the seat back sub-assembly are installed on a school bus.
 3. The modular seat frame as claimed in claim 2 wherein the first open support neck and the second open support neck are bolted to the opposed ends of the upside-down U shaped partial perimeter tube. 4-6. (canceled)
 7. The modular seat frame as claimed in claim 1 further comprising: reinforcement members located at the joints formed between the opposed ends of the upside-down U shaped partial perimeter tube and the first open support neck and the second open support neck.
 8. The modular seat frame as claimed in claim 8 further comprising: a seat back panel suspended on and within the upside-down U shaped partial perimeter tube.
 9. The modular seat frame as claimed in claim 8 wherein the seat back panel includes a partial perimeter lip by which the seat back panel is attached to the upside-down U shaped partial perimeter tube.
 10. The modular seat frame as claimed in claim 1 wherein the first riser and the second riser include integral inwardly turned flanges and back edge flanges that support front and rear cross members. 